Field of the Invention
The invention relates to an electronic apparatus, and more particularly to an electronic apparatus comprising a printed circuit board (PCB) with a plurality of memories therein.
Description of the Related Art
As printed circuit board (PCB) technology advances so that electronic apparatuses made therefrom may operate faster and be designed more densely, electromagnetic interference (EMI) problems in electronic apparatuses have increased. For example, in an electronic apparatus, a memory with high data rate may induce reflection effects at signal paths between the memory and a controller thereof when the memory is accessed by the controller. Therefore, I/O pins of a memory with on-die termination (ODT) or damping resistors disposed on the signal paths between the controller and the I/O pins of the memory without ODT are generally used to decrease the reflection effects.
Nowadays, more than one memory may be implemented in an electronic apparatus, so as to provide larger data storage areas for complex applications. However, not all of the I/O pins within a memory have ODT design for reducing reflection effects. Thus, parallel or series terminations are used on the signal paths of the I/O pins without ODT on the PCB. Parallel termination means that a termination device and the signal path of one of the I/O pins without ODT are coupled in parallel on the PCB. Series termination means that a termination device and the signal path of the one I/O pin without ODT are coupled in series on the PCB. In general, series termination is the most popular design, due to its low cost. However, the termination device will cause leakage, and the power consumption of the electronic apparatus is increased. If the termination device is not disposed on the PCB, the floating stub on the PCB that is designed to be coupled to the termination device may cause reflections due to the antenna effect.
Therefore, a PCB that is designed to reduce reflections for a plurality of memories therein is desirable.